The Oahu rail transit system’s maintenance-storage facility will undergo a redesign to upgrade the track operations there — a $4.25 million decision by project officials that scraps many of the original blueprints for how that facility was to work.

Board members overseeing the rail project approved the change order Thursday to the 43-acre facility, which is in the early stages of being built near Leeward Community College.

However, that multimillion-dollar price tag, which doesn’t include the eventual construction costs associated with the redesign, prompted several of them to question why the upgrades weren’t part of the original designs.

Keslie Hui, one of those board members, called the change order a "very expensive lesson" about proceeding too quickly with design work. The city looks to build the project "on time and on budget," Hui said. But it also must ensure that "we don’t have the same issue the next time," he added.

Addressing those questions, HART Executive Director Dan Grabauskas said the city’s design changes are happening now because for more than a year HART was unable to discuss the project with Ansaldo Honolulu JV amid multiple bid protests against that firm’s selection to design, build operate and maintain the rail cars and transit system.

Grabauskas, who took the job at HART in 2012, said his predecessors had to make a difficult choice of whether to start the design work without Ansaldo’s input or risk waiting too long if the challenges to the firm’s contract award lingered, which could result in costly delays. "No one knew how long" those challenges from rival bidders Sumitomo and Bombardier would take, he added.

The added design costs approved Thursday will go toward reconfiguring the track layout so it can support "automated train operations" that won’t require workers to manually move train cars around the yard. The changes will make the yard more expensive to build, but Grabauskas said they’ll also make it safer and less expensive to operate, although he did not have savings estimates immediately available.

It’s easier to tear up blueprints than it would be to "tear up track" later, he told board members.

The redesign also includes adding a test track at the facility, more cabling for the automated track system, a car-unloading dock and more grading and utilities.

The new plans represent 40 percent of the total design costs for the maintenance-storage facility, Lorenzo Garrido, HART’s director of engineering and construction, told the board members. The construction costs will come before the board at a later date, he added.

The maintenance-storage site has already been graded, and crews are scheduled to start laying its concrete foundations this month, according to HART officials.